Create customize ID field

By default the application developer is NOT required to coding for the @Id field". However there are some situation that we want to create our own ID field. E.g. I want all my users be indexed by facebook ID. Let’s take a look at the code first:

@Entity public class User extends Model {
    @Id public String fbId;
    
    @Override
    public Object getId() {
        return fbId;
    }
    
    @Override
    protected void setId_(Object id) {
        fbId = processId_(id);
    }
    
    protected static Object processId_(Object id) {
        return id.toString();
    }
    
    ...
}

So the above code shows what you need to do to create a customized ID field model:

Declare your ID field. You can use any name and any type for this field but it must be annotated with @com.google.code.morphia.annotations.Id.
Override Model.getId() method which returns the ID field you declared
Override Model.setId(Object) method which set the processed ID object to the ID field you declared
create Model.processId_(Object) static method which convert the object to the type of your ID field

Links:

Community contributed extensions

Create customize ID field